1. Field of the Invention
The present invention relates to a method for repairing leaks or cracks in tubes. More particularly, the present invention relates to a method for repairing hidden cracks in tubular assemblies where tubes are bundled together or bonded to a supporting shell, such as in heat exchangers. In such assemblies, the access to the area of the tube adjacent the wall is limited, and it is extremely difficult to repair leaks or fatigue cracks which develop in these areas.
2. Description of the Prior Art
Various methods have been developed for repairing damaged tubes. Such methods are disclosed in U.S. Pat. No. 3,643,701 to Wadiak et al, in which a rupture is repaired by enlarging a tube to form an opening big enough to accept a pipe section therein. Each end of the pipe section includes a gasket which can be expanded to engage the sidewalls of the tube to provide temporary repair. U.S. Pat. No. 3,807,024 to Harvey et al discloses a method of repairing a damaged tube in an upright finned tube wall in which the tube and its associated fins are cut out over the damaged region and a new length of tube secured to the cutaway region. U.S. Pat. No. 3,962,767 to Byerley et al discloses a method for repairing a heat exchanger tube in which the tube is severed and a sleeve is welded inside the tube to cover a defect in the tube. The last two mentioned patents require cutting through an entire portion of the tube and therefore cannot be conveniently employed in situations where access to the tube is restricted. The Wadiak patent is directed to a temporary repair method and requires a relatively complicated pipe section having axially expandable gaskets at each end.